SEOUL (Reuters) - North Korean leader Kim Jong Un supervised a ground test of a new rocket engine to launch satellites, the North's state media reported on Tuesday, the latest in a rapid succession of missile-related tests this year by the isolated state.

Kim asked scientists and engineers to make "preparations for launching the satellite as soon as possible on the basis of the successful test," the official KCNA news agency said, indicating the North may soon launch another long-range rocket.

The test was conducted amid global condemnation of the North's fifth nuclear test earlier this month and a call by the United States, Japan and South Korea this week for greater pressure on Pyongyang over its disregard for United Nations resolutions banning missile and nuclear programs.

North Korea has been testing nuclear weapons and ballistic missiles at an unprecedented rate this year under Kim's direction, including the launch of a satellite in February that was widely seen as a test of long-range ballistic missile technology.

The North's Rodong Sinmun newspaper carried photographs of Kim on a podium overlooking the vertical test stand that housed a rocket engine which blasted a column of flame.

A spokesman for South Korea's military, Jeon Ha-gyu, said it was likely to have been a test for a new engine that can be used for a long-range missile.

A satellite image dated Sept. 17 provided to Reuters by 38 North, a Washington-based website devoted to analysis of North Korea, showed preparations for an engine test, including a heavy crane over the vertical engine test stand and a shelter that would house the rocket engine.

"This test is another important development pointing to the first launch of a bigger, better space vehicle to place satellites in higher orbits, which could happen in the not too distant future," said Joel Wit, founder of the 38 North website.

North Korea claimed after its nuclear test this month that it had mastered the ability to mount a warhead on a ballistic missile, a worrying prospect for neighbors South Korea and Japan. Developing an effective intercontinental ballistic missile (ICBM) would put the continental United States in range of the North's nuclear weapons.

Joshua Pollack, editor of the U.S.-based Nonproliferation Review, said North Korean media's description of a rocket engine with 80 tonnes of thrust would make it "a very powerful rocket, well beyond anything the North Koreans have shown the world before."

The test, Pollack said, may be the result of cooperation with Iran.

The U.S. Treasury said in a January announcement of sanctions on people involved in Iran's missile program that Iranian technicians had in recent years "traveled to North Korea to work on an 80-ton rocket booster being developed by the North Korean government."

Chinese Foreign Ministry spokesman Lu Kang was asked at a regular briefing on Tuesday whether China considered the test part of a peaceful space program or a violation of sanctions.

"Regarding North Korea's ballistic missile launch activities, at present the Security Council has explicit stipulations. So we hope all parties can honor the relevant U.N. resolutions," Lu said.

China is North Korea's main ally but has supported U.N. sanctions against its nuclear and missile programs.

North Korea earlier this month fired three missiles that flew about 1,000 km (600 miles) each and in August tested a submarine-launched ballistic missile (SLBM) that international experts said showed considerable progress.

It also launched an intermediate-range missile in June that experts said marked a technological advance for the isolated state after several test failures.

"Kim Jong Un ... visited the Sohae Space Center to guide the ground jet test of a new type high-power engine of a carrier rocket for the geo-stationary satellite," KCNA said on Tuesday.

The Sohae center is the North's newly upgraded rocket station where the February satellite launch and other rocket tests have been conducted.